I'm trying to make a small perk with three ranks that gives you a % chance to disarm opponents on a successful unarmed attack (I'm thinking 5, 8, and 10% chance) but I don't know how to do disarms. Anyone got an idea?
EDIT: I think I need to make a Weapon Hit casts spell perk conditioned to be unarmed that casts a scripted spell. This scripted spell casts a high level disarm spell if the percentage chance comes out right.

Try giving the player an OnHit event, so that it fires when the player gets hit.

One of the parameters is a bool to tell if the attack was blocked. If it was blocked, roll the dice.

If the roll passes, the event parameters give you a reference to the aggressor and the form used to attack. If the aggressor is an actor and the form is a weapon, you can use that to remove the weapon from the actor. Maybe add a bit of havok impulse to send it flying.

Might also be worth looking at the disarm shout to see that works